My next door neighbour had the hard drive replaced in his 2007 mac about 2 months ago, by the local indecent computer repair shop (not apple store). Last week the mac died again and he diagnosed it himself as a faulty hard drive. Been the nice person i am I have agreed to replace it for him. On taking the machine apart today I have found the hard drive not to be bolted into the machine, or the temp sender attached. Would anyone know if this would give similar symptoms to a dead hard drive with a lack of a definite earth? Bit of advice would be great before he gets on the phone to the hard drive supplier and making a prat of himself!!